1. Field of the Invention
The present invention relates to artificial airway devices used to facilitate lung ventilation in unconscious patients, and more specifically to devices designed for placement above the laryngeal opening of the patient in order to prevent airway obstruction and to permit either spontaneous or controlled ventilation.
2. Description of Related Art
To maintain open the airway of an unconscious patient under general anesthesia, it is common practice to use an endotracheal tube, which is a flexible tube of rubber or plastic which is inserted down through the trachea. Prior art endotracheal tubes frequently include an inflatable cuff disposed symmetrically around a distal end of the tube, which distal end is inserted into the trachea. The inflatable cuff is used to seal and secure the endotracheal tube in place.
Typically, the endotracheal tube is introduced through mouth or nose and the larynx into the trachea or windpipe, and then the cuff is inflated through a small auxiliary tube in order to form a seal against the wall of the trachea. Introduction of the endotracheal tube into a patient is a skilled operation normally requiring use of a laryngoscope to guide the tube through the larynx, past the vocal cords and into the trachea. Intubation using an endotracheal tube is difficult or even impossible in some patients. Moreover, there is a significant risk of damage to soft tissues or to the larynx when using an endotracheal tube. Likewise, there is a risk of accidental, but highly undesirable, intubation of the esophagus or of the right or left main bronchus when using an endotracheal tube.
Alternatively, oro- or naso-pharyngeal airway devices may be used to maintain open the airway of a patient under general anesthesia. An oro- or naso-pharyngeal airway is a flexible tube extending from the mouth (oro-pharyngeal airway) or nose (naso-pharyngeal airway) into the patient""s pharynx but not into the patient""s larynx. An oro- or naso-pharyngeal airway is normally used in conjunction with a face mask over the patient""s mouth and/or nose, unlike an endotracheal tube, which normally is not used with a mask. While preventing obstruction of the airway by the tongue, an oro- or naso-pharyngeal airway device cannot be used conveniently for controlled ventilation of the patient and does not prevent inhalation of extraneous matter (i.e., aspiration). For these and other reasons this type of device is less desirable in many applications.
Prior art artificial airways (see for example, U.S. Pat. Nos. 4,509,514; 4,995,388; 5,241,956; 5,249,571; 5,282,464; 5,297,547; 5,305,743; 5,355,879; 5,584,290; 5,632,271 and 5,682,880 to Archibald I. J. Brainxe2x80x94collectively, the xe2x80x9cBrain patentsxe2x80x9d) use a curved tube and a laryngeal mask portion at one end of the tube. The mask portion includes a flexible annular inflatable collar which surrounds a hollow interior space of the mask portion. The mask portion is pre-formed with a roughly elliptical shape which is purported to be capable of conforming to, and fitting within, the space behind the larynx to form a seal around the circumference of the laryngeal inlet without penetrating into the interior of the larynx. The curved tube opens into the mask portion and provides an airway with the axis of the tube substantially aligned with the length of the elliptical formation of the mask portion.
In the Brain patents, the curved tube opens into a lumen of the mask through an aperture which is provided with flexible cross-bars to prevent the aperture from being obstructed by the epiglottis, while permitting passage of a second smaller tube, such as an endotracheal or endobronchial tube, a suction catheter, or an inspection tube such as a fiber-optic broncho- or laryngoscope.
The present invention is an artificial airway device which is designed to overcome certain shortcomings which have been discovered with the use, in practice, of artificial airways of the prior art. The present invention is also designed to be inexpensive, to be easy to insert without causing damage to the patient and without the need for a laryngoscope or other inspection instruments, and to provide an effective airway which is not readily blocked or obstructed during use.
The present invention is inexpensive to use and easy to insert and therefore appropriate for Emergency Medical Service (EMS) use. This provides advantages over the prior art; the airway devices as shown in the Brain patents can have a tendency for the uninflated collar to pleat or fold during insertion, which results in incomplete expansion of the collar during inflation. Incomplete inflation results in leakage, which prevents effective use of the artificial airway in the manner in which it is intended to be used. Furthermore, the inflatable collars often do not conform well to the airway, also resulting in leakage. In addition, it is often difficult for the individual inserting the artificial airways shown in the Brain patents to determine whether the inflatable collar is completely inflated. In order to overcome these inflation and leakage problems, artificial airways with inflatable collars are often overinflated by the individual inserting the airway to pressures sufficiently high that they can cause damage to the soft tissue against which the inflatable collar seals.
Another difficulty with prior art artificial airways using an inflatable collar, as in the Brain patents, is that it is often difficult for the individual inserting the airway to determine when the airway mask is properly in place over the larynx. This uncertainty of proper placement makes complete sealing more difficult, and also complicates insertion of the airway into the patient. Because of this difficulty, the artificial airways of the Brain patents are generally not suitable for EMS use. Additionally, artificial airways with inflatable collars, because they must be completely inflated to properly seal, require a large number of sizes to accommodate the different sizes of airways of the patients to which they are administered. Endotracheal tubes and oro- or naso-pharyngeal airways are also generally not suitable for use by EMS personnel.
Prior art artificial airways can also cause difficulties in ensuring that the artificial airway, or parts of the airway, does not accidentally enter the esophagus during insertion. Entry into the esophagus can cause damage to delicate tissues, which is undesirable and can cause severe complications for the patient. Furthermore, the prior art artificial airways often do not have adequate mechanisms to securely anchor the device in place after insertion, a feature which is important, particularly in EMS use.
The present invention is an artificial airway device used to facilitate lung ventilation in an unconscious patient and methods for using and inserting an artificial airway device, all of which overcome the shortcomings of prior art artificial airway devices. The device of the present invention includes a curved but flexible airway tube and a mask portion, which mask portion includes a mask opening portion and a seating tip. The mask portion is attached to the airway tube at a distal end of the airway tube. The mask opening portion is shaped so as to fit closely adjacent and closely over the patient""s laryngeal opening without entering into the larynx and without requiring the mask opening portion to be sealed against the larynx or laryngeal opening. The seating tip includes a series of thin, flexible fins or gills which project from a relatively rigid projecting finger extending axially from, and preferably formed integrally with, the mask opening portion. On one side of the seating tip, at least some of the fins or gills can have an undulating shape across their width, in one embodiment of the invention, to compensate for flexing or expansion of the seating tip as it seats in position. The fins or gills seat against the pharyngeal side of the cricoid, just above the esophagus. In this way, the mask can be properly located above the laryngeal opening, and can be anchored against a relatively hard surface without causing damage to delicate tissue in the esophagus or delicate tissue in or around the larynx or laryngeal opening. The seating tip, and its placement against the pharyngeal side of the cricoid, therefore provides a reference for the person inserting the artificial airway device which ensures that the mask opening portion is properly in place and adequately anchored or seated in place. The interaction between the seating tip and the pharyngeal side of the cricoid helps ensure that the individual inserting the airway accurately positions the mask opening portion, and therefore the connection to the airway tube, over the patient""s laryngeal opening. The pharyngeal side of the cricoid also serves as a relatively rigid anchoring area for the mask portion, thereby ensuring that the mask opening portion remains in position closely adjacent and closely surrounding the laryngeal opening. The mask opening portion is shaped to conform to the space around the laryngeal opening, thereby providing an airway to the laryngeal opening without having to form a seal around the circumference of the laryngeal opening and without penetrating into the interior of the larynx or the entrance to the esophagus.
The shape of the mask opening portion ensures that it closely approximates the shape of the laryngeal opening. Because the artificial airway of the present device is not required to seal against the laryngeal opening, and because the seating tip of the present invention is designed to anchor or seat against the relatively rigid pharyngeal side of the cricoid, only a few artificial airway sizes are needed to accommodate a wide range of patient airway sizes, therefore reducing the number of artificial airway sizes needed. This feature of the present invention also reduces costs, and makes the present invention more amenable to EMS use, since fewer devices, and less storage space, is needed by the EMS crew. In addition, the seating of the seating tip against the pharyngeal side of the cricoid provides a good tactile indication when the mask opening portion is properly in place in the airway, thereby enhancing the ease and accuracy of insertion of the artificial airway in the patient.
The artificial airway of the present invention is designed to be easy and convenient to insert in the majority of patients. The artificial airway may also be inexpensively manufactured in quantity, thereby allowing it to be disposable. As a result, the artificial airway of the present invention may be more readily used in EMS or other non-hospital applications, as well as in surgical applications. When the seating tip of the mask portion reaches the pharyngeal side of the cricoid above the esophagus, a definite end-point can be felt by the individual inserting the artificial airway, indicating that the mask portion is correctly placed. The mask portion does not enter the larynx or trachea, and the seating tip does not enter the esophagus, so the risk of damage to these delicate structures is avoided.
Likewise, the risk of accidental entry of the mask portion into the esophagus or one of the main bronchi is also avoided with use of the artificial airway of the present invention. Once in place, the artificial airway is generally used to allow the lungs to be ventilated by positive pressure. Alternatively, the patient may be permitted to breathe spontaneously after insertion of the artificial airway of the present invention.
The seating tip of the present invention may provide some degree of blockage so as to prevent gastric reflux from the stomach and aspiration into the patient""s airway, making the artificial airway of the present invention more adaptable to emergency and EMS use, as well as adaptable to a larger variety of surgical applications than prior art artificial airways.
The present invention also includes an inflatable cuff used to anchor the artificial airway in place using the patient""s tongue and oro-pharynx behind the uvula. This inflatable cuff is preferably offset relative to the airway tube. The offset of the inflatable cuff helps to ensure that the mask opening portion is held closely near the laryngeal opening, thereby allowing more effective operation of the artificial airway device. The inflatable cuff may be deflated so that the artificial airway device may be more easily inserted into the patient, and thereafter inflated to anchor the artificial airway device in place.
In the method of insertion of an artificial airway according to the present invention, the inflatable cuff is first deflated. The artificial airway is lubricated, and then inserted down the patient""s oral cavity. The seating tip of the artificial airway is fed along the hard and soft palate, the back of the oropharynx, and into the cricopharynx adjacent the cricoid. When resistance is felt due to interaction between the seating tip and the cricoid, insertion is halted. The artificial airway is then pulled back slightly, to lift the epiglottis away from the mask opening and so that the inflatable cuff is just behind the uvula. The inflatable cuff is then inflated. The patient may then be ventilated.